Re: SVG export - how might you add classes for all graphical objects?

[Aaron Hill]

On 2021-06-29 9:43 am, Jean Abou Samra wrote:
> However, this problem can be solved by writing
> an engraver (those are the powerful tools that
> \applyOutput uses under the hood).
>
> \version "2.22.0"
>
> \layout {
>   \context {
>     \Score
>     \consists
>       #(lambda (context)
>          (make-engraver
>            (acknowledgers
>              ((grob-interface engraver grob source-engraver)
>                 (set! (ly:grob-property grob 'output-attributes)
>                       `((class . ,(grob::name grob))))))))
>   }
> }
>
> <<
>   { c d e f }
>   \\
>   { g a b c' }
> > >

NOTE: You might want this engraver to *append* to the class attribute, 
so you can still specify classes on an individual basis:

%%%%
\version "2.22.0"

SvgAddClassName =
#(lambda (ctxt)
  (define (add-class-name grob)
   (let* ((attribs (ly:grob-property grob 'output-attributes '()))
          (class (ly:assoc-get 'class attribs '()))
          (name (grob::name grob)))
    (set! class (if (null? class) name (format #f "~a ~a" class name)))
    (set! attribs (assoc-set! attribs 'class class))
    (ly:grob-set-property! grob 'output-attributes attribs)))
  (make-engraver
   (acknowledgers
    ((grob-interface engraver grob source)
     (add-class-name grob)))))

\layout { \context { \Score \consists \SvgAddClassName } }

{ \tweak output-attributes #'((class . foo)) b'4 }
%%%%


-- Aaron Hill